The fact is, this quiet and mysterious pair, who potted alongside one another for 12 years, were out of place. Not only because they both fled to London from the Nazis (Rie from Vienna, Coper from Dresden), but because the natural clientele for their sophisticated, self-conscious creations was the educated bourgeoisie. Britain has never had a bourgeoisie, let alone an educated one.
For most Brits, pots is pots. Craft, not art. We cherish the thumbprints in the dark glaze of the country potter's urn but frown at the metropolitan potter's goitre necks.
When Rie reached London in 1938, aged 36, she was trailing clouds of the avant-garde Vienna Werkstatte, having established a golden reputation on the European exhibition circuit. But London curators and college teachers gave her rather kitschy Viennese ceramics a frosty reception. At the time, Bernard Leach, father of the 20th-century pottery revival, was casting British studio pottery in the earthy, rural, non-progressive mould for which his A Potter's Book of 1940 would be the manifesto.
It is Leach's ever-powerful craft tradition that makes us recoil from pots that are not pot-shaped. Those by both Rie and Coper - who joined her as an assistant unable to pot, but, by his death in 1981, was producing monumental forms more adventurous than her own - do not even look hand- made. Nor were they meant to. Coper made pre-production drawings, calculating the precise measurements of component parts. Both turned their pots when leather-hard, using metal blades to excise hand-made blemishes. Rie taught her students at Camberwell School of Arts and Crafts to avoid leaving "throwing rings", regarded by Leach's followers as indispensable hallmarks of the hand-made (allow the wheel to turn full circle before moving the fingers).
In the end, it was not the British middle class that rallied to Rie and Coper's new idiom but a coterie of well-to-do and influential cognoscenti who collected and exhibited their work - the architect, the late Sir Ove Arup; the designer Lord Queensberry; Lord and Lady Sainsbury; Sir David Attenborough; and, especially, Rie's close friend Cyril Frankel, film- maker and founder of the London auction market in contemporary ceramics.
The reputation-making machinery did not make a lasting impact until the Metropolitan Museum of Art in New York held a joint Rie and Coper exhibition in 1994/ 1995. Now, characteristically, US collecting-dining-lecturing groups have sprung up - and new enthusiasts are expected to push up prices at Bonhams' 17 April sale of pots from Rie's estate (she died in 1995).
Indeed, it is difficult to view the exhibition without seeing imaginary auction estimates floating above the pots: the record pounds 88,000 paid for Coper's massive pair of black candle holders; pounds 5,000 to pounds 7,000 for a Rie bottle vase. Over-priced as craft, they are under-priced as art. You can still buy a Rie masterpiece for the price of a Hockney print.
There will be no more pots like these. Who could make a flared-rim bottle vase or a spade without being accused of copying? The pair's influence lies in their breaking of craft conventions, not in the number of followers potting identical shapes. Except, perhaps, for Rie's exquisite footed bowls - versions by living potters abound. Rie did not invent the shape and it is not the shape that her devotees try to copy. It is her perfection.
`Potters in Parallel': Barbican Art Gallery, Barbican Centre, Silk Street, London EC2 to 26 May (0171-588 9023)Reuse content